From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [KVM PATCH v2 2/2] kvm: use POLLHUP to close an irqfd instead of an explicit ioctl Date: Thu, 18 Jun 2009 14:46:30 +0930 Message-ID: <200906181446.31373.rusty@rustcorp.com.au> References: <20090604124047.10544.38861.stgit@dev.haskins.net> <4A3639B2.7080006@novell.com> <20090615125439.GI6351@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Gregory Haskins , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, avi@redhat.com, davidel@xmailserver.org, paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org To: "Michael S. Tsirkin" Return-path: Received: from ozlabs.org ([203.10.76.45]:46813 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751541AbZFRFQd (ORCPT ); Thu, 18 Jun 2009 01:16:33 -0400 In-Reply-To: <20090615125439.GI6351@redhat.com> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: On Mon, 15 Jun 2009 10:24:39 pm Michael S. Tsirkin wrote: > On Mon, Jun 15, 2009 at 08:08:18AM -0400, Gregory Haskins wrote: > > Hmm. I understand what you are saying conceptually (i.e. the .text > > could get yanked before we hit the next line of code, in this case the > > "return 0"). However, holding a reference when you _know_ someone else > > holds a reference to me says that one of the references is redundant. > > In addition, there is certainly plenty of precedence for > > module_put(THIS_MODULE) all throughout the kernel (including > > module_put_and_exit()). Are those broken as well? > > Maybe not, but I don't know why. It works fine as long as you don't > unload any modules though :) Rusty, could you enlighten us please? Yep, they're almost all broken. A few have comments indicating that someone else is holding a reference (eg. loopback). But at some point you give up playing whack-a-mole for random drivers. module_put_and_exit() does *not* have this problem, BTW. Rusty.